1. Field of the Invention
The present invention relates to a transparent touch screen, and more particularly to a top-emitting OLED (Organic Light Emitting Diode) display having a transparent touch panel.
2. Description of the Related Art
Currently, OLED display devices are divided into two light emitting modes that are the bottom-emitting mode and the top-emitting mode. Since rays emitted by the organic light emitting layer of a bottom-emitting OLED may be shielded by the thin-film transistors (TFT) on the substrate, the aperture ratio is reduced by the TFTs. Therefore, the top-emitting OLED is an effective solution to improve the ratio of effective light emitting areas to total areas such that is superior to a conventional active LED display apparatus.
The touch screen is a simple, humanized and space-saving input apparatus widely applied in tourist guiding systems, automatic teller machines (ATMs), palm computers, point-of-sale (POS) terminals and industrial control systems and so on.
US Patent Publication No. US 2002/0186208 A1 discloses an electroluminescent display apparatus with a touch screen, which includes a transparent substrate, a resistive touch device disposed on one surface of the transparent substrate and an electroluminescent display device disposed on the other surface of the transparent substrate. However, the resistive touch device and the electrolurminescent device fabricated on two surfaces of the transparent substrate are likely to get scratches during the manufacturing process. Moreover, the sensitivity of the resistive touch device is relatively low.
US Patent Publication No. 2004/0080267 A1 discloses an integrated device of an organic light emitting display and a touch screen. The resistive touch device is formed on a cover in advance, and then the cover is mounted on the organic light emitting display. However, the resistive touch device has low sensitivity, and can adequately detect any input only when being pressed by an object with a sharp end, such as a pen. Therefore, the resistive touch device is easy to be scratched in use. Moreover, when the organic light emitting display is combined with the cover, the resistive touch device fabricated on the cover is easy to be damaged.
US Patent Publication No. 2004/0090426 A1 discloses an integrated device of an organic light emitting display and a touch screen. The resistive touch device is formed on the surface of the transparent substrate (or cover) of the packaged organic light emitting display. However, the fabricating method disclosed in US 2004/0090426 A1 is rather complicated, and the service life of the organic luminescent material is shortened due to the process of the resistive touch device. Moreover, the sensitivity of the resistive touch device is relatively low.
In view of the above, a touch panel capable of precisely and sensitively sensing any meaningful touches is needed urgently on the market, and its transparent structure facilitates the touch panels as a input device to be widely applied to various display screens.